There exist techniques for navigating in an image stored in a server, from a client terminal connected to this server. For example, the Quicktime VR technique makes it possible, amongst other things, to zoom in an image to the JPEG format. This technique is implemented in software available via the Internet through apple.com.
Thus, by virtue of this technique, it is possible, from the client terminal, to make zooms and translations in the image stored on the server. A viewing window restores the result of the navigation at the client terminal.
For this purpose, the image is stored at several resolutions in the server. The change from one resolution to a higher resolution is made by supersampling.
In this technique, there is strictly speaking no zoomable area in the image since it is the complete image which is zoomable.
In addition, there exist image compression techniques which make it possible to define zoomable areas. For example, image compression according to the JPEG2000 standard makes it possible to create one or more zoomable areas in the image. A zoomable area can be decoded at a greater resolution than the rest of the image.
Patent application US 2002/0105531 A1 describes a method for zooming in an image wherein data representing detail image information is loaded from a storage unit and used for presenting an area of the image in higher resolution.
In this document, the storage unit contains only data, which is processed according to instructions stored in the presentation device, in a fixed and predetermined manner.